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Solubilization of Serotonin 1a and Serotonin 1b Binding Sites from Bovine Brain
Author(s) -
Asarch Kenneth B.,
Shih Jean C.
Publication year - 1987
Publication title -
journal of neurochemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.75
H-Index - 229
eISSN - 1471-4159
pISSN - 0022-3042
DOI - 10.1111/j.1471-4159.1987.tb05691.x
Subject(s) - serotonin , solubilization , chemistry , binding site , biochemistry , receptor
Serotonin, (5‐hydroxytryptamine 1 , 5‐HT 1 ) binding sites have been solubilized from bovine brain cortex using a mixture of 0.1 % Nonidet P‐40 and 0.3% digitonin in a low‐salt buffer containing 0.1 % ascorbic acid. The affinity of [ 3 H]5‐HT for the soluble cortical binding sites (2.1 n M ) is identical to its affinity at membrane‐bound binding sites (2.1 n M ). [ 3 H]8‐Hydroxy‐2‐(di‐ n ‐propylamino)tetraIin ([ 3 H]DPAT), a selective 5‐HT 1a , radioligand, also binds to soluble cortical binding sites with high affinity (1.8 n M ) comparable with its affinity in the crude membranes (1.7 n M ). A significant correlation exists in the rank order potency of serotonergic agents for [ 3 H]5‐HT binding and for [ 3 H]DPAT binding to crude and soluble membranes. The density of [ 3 H]DPAT binding sites relative to the [ 3 H]5‐HT sites in the solubilized cortical membranes (35%) corresponds well with the proportion of 5‐HT 1a sites in the crude membranes determined by spiperone displacement (33%), suggesting that both the 5‐HT 1a and 5‐HT 1b binding sites have been cosolubilized. [ 3 H]5‐HT binding in the soluble preparations was inhibited by GTP, suggesting that a receptor complex may have been solubilized. [ 3 H]Spiperone‐specific binding was not detectable in this preparation, suggesting that 5‐HT 2 sites were not cosolubilized.